The present invention relates generally to the field of sterilization equipment, and, more specifically, to a device for surface sterilization of objects of various regular or irregular shapes, which device includes the combination of ultraviolet lamps, HEPA air filters and a pass-through sterilization chamber within a tunnel-like housing which covers a conveyor.
Previously, the pharmaceutical industry used glass bottles for the purpose of filling liquids and powder in a sterile manner in rooms which meet specific standards, referred to in the industry as "Class 100," for levels of cleanliness and sterility. The three traditional sterilization methods used are as follows: 1.) the glass bottles are passed into the clean room by sterilizing batches of bottles in a double door autoclave, loading the bottles on the "dirty" side of the autoclave, and, after sterilizing, opening the autoclave door on the clean room side, allowing the sterile bottles to be passed through the autoclave into the clean room for filling with sterile liquid; 2.) sterilizing batches of bottles in a double door hot air oven, loading the bottles on the dirty side, and as with the autoclave in number 1., after the bottles are sterilized, the oven door inside the clean room is opened, allowing the sterile bottles to be passed through manually into the clean room for filling; and 3.) using a hot air sterilizing tunnel to decontaminate the bottles, loading the bottles on the dirty side and automatically discharging them into the clean room for filling.
Although the above methods were satisfactory for sterilizing glass bottles, they cannot be used for bottles produced of the plastics now available, because all of these methods will cause the plastic bottles to melt during the sterilization process, rendering the bottles completely useless. Thus, at present, plastic bottles for filling with sterile liquids and powders are now filled and closed in what is commonly referred to in the industry as "Class 100" or "clean" rooms.
The currently used plastic bottles for sterile filling are manufactured in such clean rooms, and packaged into cardboard trays before shrink-wrapping and then exposed to gamma radiation for sterilization of the inside of the bottles. The sterile, shrink-wrapped trays of bottles are then shipped in plastic bags to customers for filling with the desired sterile substance.
The difficulty arises when a customer receives the wrapped, sterile plastic bottles. The problem lies in how to introduce the contaminated exterior bags containing the bottles into the clean room without breaking sterility of the room. Some attempts have been made to work with generators of hydrogen peroxide vapors. One example of this approach is such a vapor generator developed and currently marketed by AMSCO Scientific, a Division of American Sterilizer Co. Although with the AMSCO device hydrogen peroxide decontaminates the outer surface of the containment bag; at the same time, the vapor permeates through the plastic bag, contaminating the inside of the shrink-wrapped bottles with free radicals of hydrogen and oxygen, which may be highly undesirable in contact with the particular sterile substance to be introduced into the sterile plastic bottles.
Other disadvantages with the hydrogen peroxide vapor method are that a relative humidity of approximately 40% is necessary for vaporization, and health hazards are posed by the high levels of hydrogen peroxide vapor. Furthermore, this system requires a long period of time for the cycle of decontamination, including vapor generation and evacuation of the vapor from the package being sterilized.
Another known approach to the above described problem has been to simply place the plastic bag filled with previously sterilized bottles under a HEPA filter module pass-through unit in hopes of decontaminating the outside sufficiently that the clean room into which the bag is introduced does not break the sterile environment. Unfortunately, particularly with articles of irregular shape, such as large, loosely packed plastic bags, decontamination can be incomplete due to contaminants becoming trapped in folds and crevices of the exterior package.
Similar short-comings exist with previous uses of ultraviolet ("U.V.") or other germicidal lights, in that all surfaces of the package to be decontaminated are not necessarily accessible by the light rays.
One version of an ultraviolet light sterilizer has been available in the market place from Despatch Industries, which device is designed to transport small plastic bags of pre-sterilized items into a clean room. This version, however, does not lend itself to production line use, and can only be used for batch preparation. Furthermore, the concentric design of the equipment does not allow for good sterilization of the ends of the packages, and the heat generated by the U. V. lights is sufficient to melt plastic wrap.
Accordingly, there exists a need in the industry for a device and method for surface sterilization of items to be introduced into a clean room without breaking sterility of the room, and particularly with regard to such items which have irregular surfaces and those which may have already been sterilized, but are enclosed in an exterior wrapping which is necessarily somewhat contaminated, if only by previous exposure to the ambient environment.
Thus, in view of the above, it is among the several goals of the invention to provide a device for sterilizing the surfaces of packages, which device can be used in a production line and which can be operated automatically for continuous pass-through sterilization of packages from a "dirty" (non-clean, or not class 100" side of the device, sometimes referred to as a dirty room or area, to a clean area or room.
It is further among the goals of the present invention, having the features indicated, that the device be capable of completing a sterilization cycle in a brief period of time, such as approximately one minute, and which can function appropriately with packages of various sizes and shapes. Ideally, the device can be manufactured in various sizes so that even greater flexibility on package size and production rates of sterile product can be realized.
It is still further among the several goals of the present invention, having the features indicated, that the device be capable of sterilizing items made of plastic with out creating so much heat that such items are caused to melt in the sterilization process, and that no health risks, such as burns (from steam, or ultraviolet light) and noxious or dangerous vapors exist to personnel using the device.
The present surface sterilizing device accomplishes the above goals by providing a combination of a pass-through tunnel for the goods to be sterilized and by including within one device both HEPA filtration as well as ultraviolet light at such high intensity that the cycle can be completed very quickly, yet without intense heat build-up.
In furtherance of the above objects, the present invention is, briefly, a device for surface sterilization of objects, the device including a housing having a first end and a second end and extending continuously therebetween, a conveyor assembly including a frame, a conveyor bed selectively movably connected to the frame, and a plurality of legs spacedly disposed beneath and supporting the frame above a support surface, at least part of the conveyor bed located longitudinally within the housing, to thereby movably support objects to be surface sterilized as they are passed from a contaminated area to a clean area, an air filtration system in communication with the housing, at least one ultraviolet light assembly located within of the housing and capable of providing ultraviolet irradiation of sufficient strength for a sufficient period of time to decontaminate the object to be surface sterilized within the sterilization device as the object to be sterilized is transferred via the conveyor through the housing and into the clean area, and controls by which an operator of the device can operate the conveyor, the air filtration system and the ultraviolet lights of the device.
The invention is also, briefly, the combination of a conveyor for passing objects to be sterilized from a contaminated area to a clean area, a housing over at least part of the conveyor, and an air filtration system mounted on and in communication with the housing, wherein the housing includes a portion having at least one ultraviolet light assembly, and further wherein the air filtration system includes a HEPA filter.
The invention is further, briefly, a method of sterilizing surfaces of objects to be passed from a non-sterile area to a sterile area, the method including placing an object which is to be surface sterilized on an intake end of a conveyor which passes through a housing connecting a contaminated area to a clean area, causing the conveyor to move through the housing toward the clean area, applying HEPA air filtration along at least a part of the length of the conveyor within the housing, exposing the object on the conveyor to ultraviolet light as it is carried on the conveyor through the housing, and passing the surface sterilized object on the conveyor through an output portion of the housing and into a clean room.
These and other objects and benefits of the invention are in part apparent and in part pointed out hereinbelow.